Metal reinforced seal plate for pilot actuated spool valve
Upper and/or lower seal plates of a sub plate mounted, pilot actuated spool valve are reinforced with one or more metal rings. In a number of preferred embodiments, the metal ring is comprised of steel. Portions of the seal plates may comprise an engineering thermoplastic such as polyoxymethylene (POM) sold by E. I. DuPont de Nemours under the DELRIN® trademark. The plastic material may be molded to the metal ring. In other embodiments, the plastic material and metal ring(s) are mechanically connected together.
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This application is a continuation of U.S. application Ser. No. 14/958,359 filed on Dec. 3, 2015, which is a divisional of U.S. application Ser. No. 13/633,701 filed on Oct. 2, 2012, which claims the benefit of U.S. Provisional Application No. 61/655,862, filed on Jun. 5, 2012.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENTNot Applicable
BACKGROUND OF THE INVENTION1. Field of the Invention
This invention relates to valves. More particularly, it relates to sub plate mounted, pilot actuated spool valves.
2. Description of the Related Art including information disclosed under 37 CFR 1.97 and 1.98
U.S. Pat. No. 5,771,931 to Watson discloses a reciprocating sleeve type valve mechanism having a valve housing within which is located a cage element. A piston, movably positioned within the valve housing, accomplishes linear opening movement of a cylindrical seal sleeve with respect to spaced polymer seals within the housing. Closing movement of the seal sleeve is accomplished by a return spring. Sealing between the cage element and a wear resistant external ceramic liner of the seal sleeve is accomplished by a seal assembly having a centrally located elastomer seal ring with polymer backup wiper rings positioned on opposite sides thereof. The seal assembly provides a bearing and guiding function to stabilize the seal sleeve during its opening and closing movement and to wipe particulate from the sealing surface of the seal sleeve as well as to maintain efficient sealing with the seal sleeve as the valve is opened and closed.
U.S. Pat. No. 4,887,643 to Tomlin et al. describes a housing that has a cage with supply fluid ports, vent ports and an outlet port. A pilot actuated hollow spool valve element is telescopically movable in the cage and engages poppet seats at opposite ends of the cage. Elongated supply and vent slots directed transversely to the axis of the cage and valve element provide maximum flow passages. The ends of the spool are in contact with the cage at all times and the axial extent of the contact between the spool and the cage is greater than fifty percent. The spool engages the interior of the cage at the fluid ports and vent ports for reducing flow restrictions. A recess coaxially positioned at each end of the cage receives one of the valve seats. The housing abuts the cage for properly loading the valve seats. A dash pot cushions the valve element. A pilot control stem is connected to the valve element exteriorly of the valve element. A seal carrier provides a seal between mating surfaces of an underwater control pod.
U.S. Pat. No. 4,457,489 to Gilmore describes subsea fluid conduit connections for remote controlled valves.
It has been found that the polymer seal plates in valves of this type tend to distort by bowing when subjected to higher pressures. The present invention solves this problem.
BRIEF SUMMARY OF THE INVENTIONUpper and/or lower seal plates of a sub plate mounted, pilot actuated spool valve are reinforced with a metal ring. In a number of preferred embodiments, the metal ring is comprised of steel. The seal plates may comprise an engineering thermoplastic such as polyoxymethylene (POM) sold by E. I. DuPont de Nemours under the DELRIN® trademark. The plastic material may be molded to the metal ring. In other embodiments, formed plastic material and a metal ring(s) are mechanically connected together.
The invention may best be understood by reference to the exemplary embodiment(s) illustrated in the drawing figures and described, below.
The valve is actuated by piston 104 which is responsive to hydraulic pressure supplied via pilot pressure port 114. Outer spring 108 and concentric inner spring 110 acting against end plate 112 return piston 104 to the position shown in
The lower portion of valve 100 comprises upper polymer seal 130, valve cage 116, lower polymer seal 140 and valve spool or seal sleeve 118. Spool 118 slides within the inner bore of cage 116 in response to the action of valve stem 106 which is connected to piston 104. T-seal 120 and wipers/back-up seals 122 provide a seal between the inner bore of valve cage 116 and the outer, cylindrical surface of spool 118. The outer surface of valve cage 116 has a circumferential groove for holding O-ring seal 124 for sealing to the walls of the bore in valve housing 102.
Valve spool 118 includes upper annular sealing surface 126 which bears against surface 136 of seal 130 when the valve is in the closed position and lower annular sealing surface 128 which bears against surface 146 of seal 140 when the valve is in the open position.
Upper disk seal 130 includes a perimeter groove for O-ring seal 132 and a groove in the wall of its central axial opening for shaft seal 134. Likewise lower seal 140 has a perimeter groove for retaining O-ring seal 142. In the illustrated valve, central axial opening 144 of seal disk 140 is internally threaded for engagement with an insertion/removal tool (not shown).
The illustrated seals plates may be used as the upper seal plate and, in certain embodiments, as the lower seal plate. Those skilled in the art will appreciate that embodiments intended for use as the lower seal plate need not have the groove on the inside diameter of the central axial opening for accommodating a seal. Instead, the central axial opening in the lower seal plate may be internally threaded to facilitate the insertion and removal of the seal plate from the bore by attachment to a matching, externally-threaded tool.
In operation, the function port is in fluid communication with the vent port via vent port openings 152 in valve cage 116 when valve 100 is in the closed position. In the closed condition, supply port fluid communication with central passageway 154 via supply flow port openings 150 in valve cage 116 (and hence the function port) is blocked by the sealing engagement of sealing surface 125 with seal 130. When valve 100 is in the open position, spool 118 moves downward (as oriented in
It has been found, in practice, that the pressure of sealing surface 126 on polymer seal 130 and the pressure of sealing surface 128 on polymer seal 140 can, over time, cause those seals to deform. Most often, the deformation is manifest as a coning of the seal plate—i.e., the center portion of the seal plate is axially deflected towards the spool. Such deformation can compromise the sealing effectiveness of the valve.
As indicated by the crosshatch patterns in the drawing figures, seal plates according to the invention comprise at least two materials of differing properties. The portion of the seal plate that contacts the sealing surface of the spool valve comprises a thermoplastic material. Other portions of the seal plate are fabricated from a harder and/or stiffer material such as a metal. One particular preferred metal is steel. This combination of materials provides a seal plate with enhanced dimensional stability and resistance to deformation while preserving the sealing effectiveness of the single-material seal plates of the prior art.
Portions of the seal plate may comprise DELRIN® polyoxymethylene or similar polymers. Polyoxymethylene (POM), also known as acetal, polyacetal and polyformaldehyde is an engineering thermoplastic used in precision parts that require high stiffness, low friction and excellent dimensional stability. Like many other synthetic polymers, it is produced by different chemical firms with slightly different formulas and is therefore sold under many commercial names such as DELRIN® (E. I. du Pont de Nemours and Company 1007 Market St. Wilmington Del.), CELCON® (Celanese Corporation of America 180 Madison Ave. New York N.Y.), HASTAFORM® (Hoechst Aktiengesellscfhaft Industriepark Höchst Frankfurt am Main Germany D65926) etc.
POM is characterized by its high strength, hardness and rigidity to ˜40° C. POM has a density of ρ=1.410-1.420 g/cm3 and is intrinsically opaque white, due to its highly crystalline composition. POM is a tough material with a very low coefficient of friction, high abrasion resistance, high heat resistance and low water absorption. It is dimensionally stable under exposure to moisture and heat; resistant to chemicals, solvents, flexing and creep; and has a high gloss and low friction surface.
A polyoxymethylene thermoplastic polymer may be obtained by the ionically-initiated polymerization of formaldehyde+CH2 to obtain a linear molecule of the type —CH—CH∛CH2—. Single molecules may have over 1500 —CH2— units. Because the molecule has no side chains, dense crystals are formed.
POM is commercially supplied in a granulated form and can be formed into the desired shape by applying heat and pressure. The two most common forming methods employed are injection molding and extrusion. Rotational molding and blow molding are also possible.
When supplied as extruded bar or sheet, POM may be machined using traditional methods such as turning, milling, drilling etc.
Other engineering plastics and thermoplastics may also be used to fabricate the seal plates of the present invention.
Referring now to
Central axial bore 408 may have undercut groove 410 in its inner wall for retaining a seal which may be a T-seal (such as is illustrated in
Metal reinforcing ring 414 is molded within thermoplastic body 412 to provide additional strength to seal plate 400. In one particular preferred embodiment metal reinforcing ring 414 is steel and thermoplastic body 412 comprises [or is comprised of] DELRIN® polyoxymethylene. Seal plate 400 may be formed by injection molding or other molding methods known in the art. The mold cavity may be provided with means for properly locating reinforcing ring 414 within the cavity prior to and during injection of the thermoplastic material. Following cooling of body 412, surfaces 402, 404 and/or 416 may be smoothed and polished as necessary by machining and/or grinding as is well-known in the art. Seal grooves 406 and 410 may be molded into body 412 or subsequently machined into body 412. Metal reinforcing ring 414 may be machined, die stamped from sheet stock, cut from rod stock, molded from molten material or any other technique known in the art.
Referring now to
Central axial bore 409 may have internal threads 411 for engaging an insertion and removal tool (not shown) having a corresponding, externally-threaded shaft.
Metal reinforcing ring 415 is molded within thermoplastic body 413 to provide additional strength to seal plate 401. In one particular preferred embodiment metal reinforcing ring 415 is steel and thermoplastic body 413 comprises [or is comprised of] DELRIN® polyoxymethylene. Seal plate 401 may be formed by injection molding or other molding methods known in the art. The mold cavity may be provided with means for properly locating reinforcing ring 415 within the cavity prior to and during injection of the thermoplastic material. Following cooling of body 413, surfaces 403, 404 and/or 417 may be smoothed and polished as necessary by machining and/or grinding as is well-known in the art. Seal groove 407 and threads 411 may be molded into body 413 or subsequently machined or cut into body 413. Metal reinforcing ring 415 may be machined, die stamped from sheet stock, cut from rod stock, molded from molten material or any other technique known in the art.
Referring now to
Central axial bore 508 may have undercut groove 510 in its inner wall for retaining a seal which may be a T-seal (such as is illustrated in
Metal seal plate 500 comprises annular cavity 522 having a generally T-shaped cross section (see
As shown in phantom in
Referring now to
Central axial bore 509 may have internal threads 511 for engaging an insertion and removal tool (not shown) having a corresponding, externally-threaded shaft.
Metal seal plate 501 comprises annular cavity 523 having a generally L-shaped cross section (see
As shown in phantom in
Referring now to
Central axial bore 608 may have undercut groove 610 in its inner wall for retaining a seal which may be a T-seal (such as is illustrated in
When assembled (as shown in
Thermoplastic insert 618 may be machined, molded or formed by other methods known in the art. The upper surface of insert 618 may be provided with an annular groove for retaining seal 628 which may be an O-ring seal.
As shown in phantom in
Referring now to
Central axial bore 708 may have undercut groove 710 in its inner wall for retaining a seal which may be a T-seal (such as is illustrated in
As shown in
In one particular preferred embodiment, metal body 720 is steel and thermoplastic insert 718 comprises [or is comprised of] DELRIN® polyoxymethylene. Metal body 720 may be formed by machining a metal blank or by other methods known in the art. The exposed surface of insert 718 (at lower surface 704) may be smoothed and/or polished as necessary by machining and/or grinding as is well-known in the art to make its surface flush with lower surface 704 of metal body 720.
Thermoplastic insert 718 may be machined, molded or formed by other methods known in the art. The upper surface of insert 718 may be provided with an annular groove for retaining seal 728 which may be an O-ring seal.
As shown in phantom in
Referring now to
Central axial bore 808 may have undercut groove 810 in its inner wall for retaining a seal which may be a T-seal (such as is illustrated in
As shown in
In one particular preferred embodiment, metal body 820 is steel and thermoplastic insert 818 comprises [or is comprised of] DELRIN® polyoxymethylene. Metal body 820 may be formed by machining a metal blank or by other methods known in the art. The exposed surface of insert 818 (at lower surface 804) may be smoothed and/or polished as necessary by machining and/or grinding as is well-known in the art to make its surface flush with lower surface 804 of metal body 820.
Thermoplastic insert 818 may be machined, molded or formed by other methods known in the art. The upper surface of insert 818 may be provided with annular groove 850 for retaining seal 828 which may be an O-ring seal.
As shown in phantom in
Referring now to
Seal plate 900 comprises metal body portions 930 and 932 which screw together to produce a generally ring-shaped seal plate having upper, generally planar surface 902, an opposing, lower, generally planar surface 904 with a central, axial opening 908 providing a passage from upper surface 902 to lower surface 904. Perimeter surface 916 is generally cylindrical and may have circumferential groove 906 for retaining a seal which may be an O-ring seal for sealing between the seal plate 900 and the bore of the mounting plate in which the valve is inserted.
Central axial bore 908 may have undercut groove 910 in its inner wall for retaining a seal which may be a T-seal (such as is illustrated in
Body portion 932 is generally disk-shaped and externally threaded. Body portion 930 is generally ring-shaped and internally threaded. Spanner holes 944 in body portion 932 and spanner holes 946 in body portion 930 may be provided to accommodate a tool (not shown) for assembling and disassembling upper seal plate 900.
When assembled (as shown in
Thermoplastic insert 918 may be machined, molded or formed by other methods known in the art. The inner surface of insert 918 may be provided with annular groove 952 for retaining seal 954 which may be an O-ring seal. Inner perimeter groove 956 may be provided below the threaded portion of body section 930 for retaining seal 958 which may be an O-ring seal. Seals 954 and 958 may provide a fluid-tight seal between thermoplastic insert 918 and metal body portions 930 and 932, respectively.
As shown in phantom in
Referring now to
Seal plate 1000 comprises metal body portions 1030, 1032 and 1036 which are held together by machine screws 1060 to produce a generally ring-shaped seal plate having upper, generally planar surface 1002, an opposing, lower, generally planar surface 1004 with a central, axial opening 1008 providing a passage from upper surface 1002 to lower surface 1004. Perimeter surface 1016 is generally cylindrical and may have circumferential groove 1006 for retaining a seal which may be an O-ring seal for sealing between the seal plate 1000 and the bore of the mounting plate in which the valve is inserted.
Central axial bore 1008 may have undercut groove 1010 in its inner wall for retaining a seal which may be a T-seal (such as is illustrated in
Body portion 1036 is generally disk-shaped and has annular projection 1072 on its undersurface. Countersunk holes 1062 are sized and spaced for receiving screws 1060 and pass from the upper surface of disk 1036 to the underside thereof. Body portions 1030 and 1032 are generally ring-shaped and have a plurality of threaded bores 1064 sized and spaced to receive and engage machine screws 1060.
Body portion 1030 has inner shoulder 1070 and body portion 1032 has outer shoulder 1070′. When assembled, shoulders 1070 and 1070′ together form a rabbet into which annular projection 1072 on the underside of disk 1036 may fit. This rabbet joint may produce more precise alignment of the body portions 1030, 1032 and 1036 than that provided by screws 1060, alone.
When assembled (as shown in
Thermoplastic insert 1018 may be machined, molded or formed by other methods known in the art. The outer, perimeter surface of insert 1018 may be provided with shoulder 1066 for retaining seal 1074 which may be an O-ring seal. The inner surface of generally ring-shaped thermoplastic insert 1018 may comprises shoulder 1068 for retaining seal 1076 which may be an O-ring seal. Seals 1074 and 1076 may provide a fluid-tight seal between thermoplastic insert 1018 and metal body portions 1030, 1032 and 1036.
As shown in phantom in
Referring now to
Seal plate 1100 is similar to seal plate 1000 illustrated in
Central axial bore 1108 may have groove 1110 in its inner wall for retaining a seal which may be a T-seal (such as is illustrated in
Body portion 1136 is generally disk-shaped. Countersunk holes 1162 are sized and spaced for receiving screws 1160 and pass from the upper surface of disk 1136 to the underside thereof. Body portions 1130 and 1132 are generally ring-shaped and have a plurality of threaded bores 1064 sized and spaced to receive and engage machine screws 1160.
When assembled (as shown in
Metal body portion 1130 may have perimeter shoulder 1180. When assembled (as shown in
Thermoplastic insert 1118 may be machined, molded or formed by other methods known in the art. The outer, perimeter surface of insert 1118 may be provided with shoulder 1166 for retaining seal 1174 which may be an O-ring seal. The inner surface of thermoplastic insert 1118 may comprises shoulder 1168 for retaining seal 1176 which may be an O-ring seal. Seals 1174 and 1176 may provide a fluid-tight seal between thermoplastic insert 1118 and metal body portions 1130, 1132 and 1136.
As shown in phantom in
Although particular embodiments of the present invention have been shown and described, they are not intended to limit what this patent covers. One skilled in the art will understand that various changes and modifications may be made without departing from the scope of the present invention as literally and equivalently covered by the following claims.
Claims
1. A seal for a pilot-actuated spool valve comprising:
- a metal disk having a generally planar upper surface, a generally planar lower surface, a central axial opening extending from the upper surface to the lower surface and a stepped outer surface having a first portion with a first outside diameter and a second portion having a second outside diameter greater than the first outside diameter;
- a metal ring having a generally planar upper surface, a generally planar lower surface, a central axial opening extending from the upper surface to the lower surface and having a first portion with a first inside diameter substantially equal to the first outside diameter of the metal disk and a second portion having a second inside diameter greater than the first inside diameter, the ring having first outer portion having a first thickness, a second, inner portion having a second thickness less than the first thickness and a third portion intermediate the first portion and the second portion having a third thickness less than the second thickness such that when the metal disk and metal ring are pressed together with an interference fit between the first portion of the metal disk and the first portion of the metal ring an annular cavity is formed between the metal disk and the metal ring open to the lower surface; and
- an engineering thermoplastic insert in the cavity having a surface substantially flush with the lower surface of the metal disk and metal ring.
2. The seal for a pilot-actuated spool valve recited in claim 1 wherein the engineering thermoplastic insert comprises polyoxymethylene.
3. The seal for a pilot-actuated spool valve recited in claim 1 further comprising a groove in the upper surface of the thermoplastic insert and a seal within the groove.
4. The seal for a pilot-actuated spool valve recited in claim 3 wherein the seal within the groove in the upper surface of the thermoplastic insert is an O-ring seal.
| 4436316 | March 13, 1984 | Karr, Jr. |
| 4457489 | July 3, 1984 | Gilmore |
| 4535827 | August 20, 1985 | Seaford |
| 4887643 | December 19, 1989 | Koomey |
| 5522603 | June 4, 1996 | Naitou |
| 5618047 | April 8, 1997 | Belter |
| 5771931 | June 30, 1998 | Gilmore |
| 6932354 | August 23, 2005 | Kane |
| 579896 | January 1994 | EP |
| 584480 | March 1994 | EP |
- Combined Search and Examination Report from corresponding United Kingdom Patent Application No. 1309733.2, dated Dec. 2, 2013.
- Combined Search and Examination Report from corresponding United Kingdom Patent Application No. 1410451.7, dated Jul. 3, 2014.
Type: Grant
Filed: Jan 31, 2017
Date of Patent: Apr 2, 2019
Patent Publication Number: 20170138486
Assignee: Hunting Energy Services, Inc. (Stafford, TX)
Inventors: Robert E. Smith, III (Missouri City, TX), Frank Harold Hollister (Sugar Land, TX), Richard R. Watson (Missouri City, TX), Dane Tipton (Richmond, TX)
Primary Examiner: Vishal A Patel
Application Number: 15/421,021
International Classification: F16J 15/12 (20060101); F16K 25/00 (20060101); F16K 1/42 (20060101); F16K 11/044 (20060101); F16K 1/46 (20060101);
